Exhaust-gas turbocharger

ABSTRACT

The invention relates to an exhaust-gas turbocharger ( 1 ) having a turbine ( 2 ) which has the following parts: a turbine wheel ( 3 ); a turbine housing ( 4 ) in which is arranged at least one turbine channel ( 5, 5′ ) which has a passage opening ( 6, 6′ ) arranged upstream of the turbine wheel ( 3 ) as viewed in the exhaust-gas flow direction; and a shut-off device ( 7 ), which is arranged downstream of the turbine channel ( 5, 5′ ) and upstream of the turbine wheel ( 3 ), for opening and closing the passage opening ( 6, 6′ ), wherein the shut-off device ( 7 ) has a shut-off sleeve ( 12 ) which is guided in a translatorially movable fashion in a groove ( 13 ) formed directly into the turbine housing ( 4 ).

The invention relates to an exhaust-gas turbocharger according to the preamble of claim 1.

An exhaust-gas turbocharger of said type is known from DE 10 2007 060 415 A1. Said known exhaust-gas turbocharger has a shut-off device with first and second guide grate elements, wherein the second guide grate element is guided in a translatorially movable fashion in a sleeve or bush which must be inserted into the turbine housing.

Since said sleeve is consequently a separate component which must be pre-produced and then mounted in the turbine housing, the production and assembly expenditure of the generic exhaust-gas turbocharger is relatively high.

It is therefore an object of the present invention to provide an exhaust-gas turbocharger of the type specified in the preamble of claim 1, which is of simpler construction with regard to the number of required components and which is accordingly simpler to assemble.

Said object is achieved by means of the features of claim 1.

Since the shut-off device has a shut-off sleeve which is inserted into a groove of the turbine housing and which is guided therein in a translatorially movable fashion, it is no longer necessary for a separate sleeve or bush to be produced and arranged in the turbine housing. This is because the groove in which the shut-off sleeve is guided is formed directly into the material of the turbine housing itself proceeding from the bearing housing side. Here, the groove has only a depth which is selected to be as small as possible. Said groove depth corresponds to the width of the shut-off sleeve. The outer diameter of the shut-off sleeve is smaller than the diameter of the turbine housing on the bearing housing side, such that after the groove is formed into the material of the turbine housing, the shut-off sleeve can be inserted into the groove proceeding from the bearing housing side.

This yields an integration of the shut-off device into the turbine housing upstream of the turbine inlet, in order for example to realize a so-called “turbo engine brake” with the capability to allow the exhaust-gas recirculation rate to be increased by means of regulated shut-off or throttling of the turbine channel or of the turbine channels.

It is thus possible in the case of single-stage and also two-stage regulated exhaust-gas turbochargers for the turbine channel, or in the case of two turbine channels, one or both channels, to be shut off or throttled in a regulated fashion and opened.

This yields the following advantages:

increase in the exhaust-gas recirculation rate, in order to improve exhaust-gas emissions, by means of an increase in the exhaust-gas counterpressure at part load and/or low engine rotational speeds;

improvement in the dynamic response behavior of the engine by influencing the inflow rate to the turbine wheel;

improvement in regulated braking operation with increase in braking power and improvement in the dynamic acceleration of the turbocharger and therefore also of the engine from engine braking operation;

reduction in number of components, because in contrast to the prior art, it is no longer necessary for a separate component in the form of a sleeve or bush for guiding the shut-off sleeve to be installed in the turbine housing.

The subclaims relate to advantageous embodiments of the invention.

The shut-off sleeve preferably has two webs which are arranged diametrically opposite one another and whose free ends are connected to an actuating device which effects the translatory movement of the shut-off sleeve within the groove.

To be able to connect the webs to the actuating device, the groove which is integrated into the turbine housing above the turbine wheel contour has housing apertures through the turbine housing. The number of housing apertures corresponds to the number of webs, which means that at least one housing aperture is provided whose position can be freely selected, or in the case of two webs, whose positions should be selected so as to be approximately diametrically opposite one another.

When the sleeve is inserted into the groove, an air bearing arrangement is formed, and the webs are guided through the housing apertures so as to project out of the turbine housing on the side of the turbine outlet. It is therefore possible for the shut-off sleeve to be connected to the actuating device via a suitable lever arrangement and a fork connected thereto, wherein the fork is connected at one side to the lever arrangement and at the other side to the free ends of the webs projecting from the turbine housing.

The design of the shut-off device according to the invention has the further advantage that it can be integrated into already existing turbine housings by re-working, since it is necessary merely to form the discussed groove for the shut-off sleeve into the turbine housing and to provide a number of housing apertures corresponding to the number of webs of the shut-off sleeve.

Further details, advantages and features of the invention will emerge from the following description of exemplary embodiments on the basis of the appended drawing, in which:

FIG. 1 shows a schematically highly simplified illustration of an exhaust-gas turbocharger according to the invention,

FIG. 2 shows an enlarged sectional illustration of a part of the turbine housing of the exhaust-gas turbocharger for explaining the design of a shut-off device,

FIG. 3 shows a simplified perspective illustration of a shut-off sleeve of the shut-off device according to the invention together with a lever arrangement and a fork, and

FIG. 4 shows a simplified plan view of the lever arrangement and fork according to FIG. 3.

FIG. 1 shows a schematically highly simplified illustration of an exhaust-gas turbocharger 1 according to the invention. The exhaust-gas turbocharger 1 has a turbine 2 with a turbine wheel 3 which is arranged in a turbine housing 4. In the illustrated example, the turbine housing 4 has a turbine channel 5, though it is preferable for normally two separate turbine channels to be provided, which will be described in more detail below on the basis of FIG. 2. The turbine channel 5 has a passage opening 6 which, as viewed in the exhaust-gas flow direction, is provided in the turbine housing 4 upstream of the turbine wheel 3.

Also shown in a schematically highly simplified illustration is a shut-off device 7, which is provided downstream of the turbine channel 5 and upstream of the turbine wheel 3, for opening and closing the passage opening 6.

The exhaust-gas turbocharger 1 also has the other conventional parts, in particular a compressor 8 with a compressor wheel 9 in a compressor housing 10 and a shaft 11 on which the turbine wheel 3 and the compressor wheel 9 are arranged in the conventional way. Aside from said parts, all the other parts of conventional exhaust-gas turbochargers are of course also provided, such as a bearing housing with a bearing arrangement for the shaft 11, but said parts are neither illustrated nor described because they need not be described for the explanation of the principles of the present invention.

FIG. 2 shows a schematically simplified sectional illustration of a part of the turbine housing 4 in the region of the shut-off device 7. The embodiment according to

FIG. 2 shows a turbine housing 4 with two adjacent channels 5, 5′ separated from one another by a web 20. The turbine channels 5 and 5′ have associated passage openings 6 and 6′ respectively.

FIG. 2 shows that the shut-off device 7, which is integrated in the turbine housing 4 downstream of the two turbine channels 5, 5′ and upstream of the turbine wheel 3, has a shut-off sleeve 12 which is movable in a translatory fashion in a groove 13 as symbolized by the double arrow T. Furthermore, the sectional illustration of FIG. 2 shows that the shut-off sleeve 12 is provided with webs, of which only the web 14 is visible in FIG. 2 on account of the selected illustration. The groove 13, which is formed directly into the turbine housing 4 proceeding from the bearing housing side L, is provided with housing apertures, of which only the housing aperture or the passage opening 21 is visible in FIG. 2. The number of housing apertures 21 is dependent on the number of webs with which the shut-off sleeve 12 is provided. The housing aperture 21 through the turbine housing 4 allows the webs, in the case of the illustration of FIG. 2 the web 14, to extend through into the region of the turbine outlet A, such that the free end 16 of the web 14 can be connected to a fork 19 which will be described in detail below.

From the illustration of FIG. 3, which shows the shut-off sleeve 12 on its own without the turbine housing 4, it can be seen that, in the selected example, the shut-off sleeve 12 is provided with two webs 14 and 15 which are arranged diametrically opposite one another on an edge 22 of the shut-off sleeve 12. The shut-off sleeve 12 and the webs 14, 15 preferably form a single part.

As shown in FIG. 3, the free ends 16 and 17 of the webs 14 and 15 respectively are connected to the free ends 23 and 24 respectively of the fork 19, which in turn is connected in a central region 25 to a lever arrangement 18 which is connected to an actuator or actuating element (not illustrated in FIG. 3) for actuating the shut-off sleeve 12. Here, the double arrows B1, B2 and B3 indicate the movements of the lever arrangement 18 and of the fork 19, which ultimately lead to the translatory movement T within the groove 13.

FIG. 4 serves to additionally illustrate the design and mode of operation of the lever arrangement 18 and fork 19 by way of a plan view thereof By means of the above-described embodiment of the shut-off device 7 and of the groove 13 formed directly into the turbine housing 4 proceeding from the bearing side L, it is possible to make do without further parts such as for example a guide bush for the shut-off sleeve 12, such as is known from the prior art, which reduces the production expenditure for the exhaust-gas turbocharger according to the invention, and the expenditure for the assembly thereof, considerably in relation to known designs.

In addition to the written disclosure of the invention, reference is hereby made explicitly to the diagrammatic illustration thereof in FIGS. 1 to 4.

List of Reference Symbols

-   1 Exhaust-gas turbocharger -   2 Turbine -   3 Turbine wheel -   4 Turbine housing -   5, 5′ Turbine channels -   6, 6′ Passage openings -   7 Shut-off device -   8 Compressor -   9 Compressor wheel -   10 Compressor housing -   11 Shaft -   12 Shut-off sleeve -   13 Groove -   14, 15 Webs -   16, 17 Free ends of the webs -   18 Lever arrangement -   19 Fork -   20 Separating web of the turbine housing between the channels 5, 5′ -   21 Housing apertures/passage openings -   22 Edge of the shut-off sleeve 12 -   23, 24 Free ends of the fork 19 -   25 Central region of the fork -   L Bearing housing side -   A Turbine outlet -   T Double arrow symbolizing the translatory mobility of the shut-off     sleeve 12 -   B1-B3 Movements of the lever arrangement 8 and of the fork 19 for     actuating the shut-off sleeve 12 

1. An exhaust-gas turbocharger (1) having a turbine (2) which has the following parts: a turbine wheel (3); a turbine housing (4) in which is arranged at least one turbine channel (5, 5′) which has a passage opening (6, 6′) arranged upstream of the turbine wheel (3) as viewed in the exhaust-gas flow direction; and a shut-off device (7), which is arranged downstream of the turbine channel (5, 5′) and upstream of the turbine wheel (3), for opening and closing the passage opening (6, 6′), wherein the shut-off device (7) has a shut-off sleeve (12) which is guided in a translatorially movable fashion in a groove (13) formed directly into the turbine housing (4).
 2. The exhaust-gas turbocharger as claimed in claim 1, wherein the shut-off sleeve (12) has at least one web (14) whose free end (16) is connected to an actuating device.
 3. The exhaust-gas turbocharger as claimed in claim 1, wherein the shut-off sleeve (12) has preferably two webs (14, 15) which are arranged approximately diametrically opposite one another and whose free ends (16 17) are connected to an actuating device.
 4. The exhaust-gas turbocharger as claimed in claim 2, wherein the shut-off sleeve (12) is connected to the actuating device via a lever arrangement (18) and a fork (19) which is fastened to the free ends (16, 17) of the webs (14, 15).
 5. The exhaust-gas turbocharger as claimed in claim 2, wherein the groove (13) has a number of housing apertures (21) in the direction of the turbine outlet (A) corresponding to the number of webs (14, 15).
 6. The exhaust-gas turbocharger as claimed in claim 1, wherein the turbine housing (4) has two turbine channels (5, 5′) which are arranged adjacent to one another and separate from one another and which have associated passage openings (6, 6′).
 7. The exhaust-gas turbocharger as claimed in claim 1, wherein the turbine channels (5, 5′) of the turbine housing (4) are of different sizes. 